Support custom host on listen address

Previously, the testserver could only listen on localhost. This meant
that there was no way to spin up an instance of the testserver on one
machine and access it from another. This commit adds support for custom
hosts so that the testserver can be accessed from outside hosts if
needed.

testserver/testserver.go

@@ -82,6 +82,7 @@ const defaultStoreMemSize = 0.2
 
 const defaultInitTimeout = 60
 const defaultPollListenURLTimeout = 60
+const defaultListenAddrHost = "localhost"
 
 const testserverMessagePrefix = "cockroach-go testserver"
 const tenantserverMessagePrefix = "cockroach-go tenantserver"
@@ -225,6 +226,7 @@ type testServerArgs struct {
 	storeMemSize                float64 // the proportion of available memory allocated to test server
 	httpPorts                   []int
 	listenAddrPorts             []int
+	listenAddrHost              string
 	testConfig                  TestConfig
 	nonStableDB                 bool
 	customVersion               string // custom cockroach version to use
@@ -335,6 +337,15 @@ func AddListenAddrPortOpt(port int) TestServerOpt {
 	}
 }
 
+// ListenAddrHostOpt is a TestServer option that can be passed to
+// NewTestServer to specify the host for Cockroach to listen on. By default,
+// this is `localhost`, and the most common override is 0.0.0.0.
+func ListenAddrHostOpt(host string) TestServerOpt {
+	return func(args *testServerArgs) {
+		args.listenAddrHost = host
+	}
+}
+
 // StopDownloadInMiddleOpt is a TestServer option used only in testing.
 // It is used to test the flock over downloaded CRDB binary.
 // It should not be used in production.
@@ -397,6 +408,7 @@ func NewTestServer(opts ...TestServerOpt) (TestServer, error) {
 	serverArgs.storeMemSize = defaultStoreMemSize
 	serverArgs.initTimeoutSeconds = defaultInitTimeout
 	serverArgs.pollListenURLTimeoutSeconds = defaultPollListenURLTimeout
+	serverArgs.listenAddrHost = defaultListenAddrHost
 	for _, applyOptToArgs := range opts {
 		applyOptToArgs(serverArgs)
 	}
@@ -550,8 +562,16 @@ func NewTestServer(opts ...TestServerOpt) (TestServer, error) {
 				startCmd,
 				secureOpt,
 				storeArg,
-				fmt.Sprintf("--listen-addr=localhost:%d", serverArgs.listenAddrPorts[i]),
-				fmt.Sprintf("--http-addr=localhost:%d", serverArgs.httpPorts[i]),
+				fmt.Sprintf(
+					"--listen-addr=%s:%d",
+					serverArgs.listenAddrHost,
+					serverArgs.listenAddrPorts[i],
+				),
+				fmt.Sprintf(
+					"--http-addr=%s:%d",
+					serverArgs.listenAddrHost,
+					serverArgs.httpPorts[i],
+				),
 				"--listening-url-file=" + nodes[i].listeningURLFile,
 				joinArg,
 				"--external-io-dir=" + serverArgs.externalIODir,
@@ -562,7 +582,7 @@ func NewTestServer(opts ...TestServerOpt) (TestServer, error) {
 				startCmd,
 				"--logtostderr",
 				secureOpt,
-				"--host=localhost",
+				fmt.Sprintf("--host=%s", serverArgs.listenAddrHost),
 				"--port=" + strconv.Itoa(serverArgs.listenAddrPorts[0]),
 				"--http-port=" + strconv.Itoa(serverArgs.httpPorts[0]),
 				storeArg,

testserver/testserver_test.go

@@ -49,6 +49,12 @@ func TestRunServer(t *testing.T) {
 			name:          "Insecure",
 			instantiation: func(t *testing.T) (*sql.DB, func()) { return testserver.NewDBForTest(t) },
 		},
+		{
+			name: "InsecureWithHostOverride",
+			instantiation: func(t *testing.T) (*sql.DB, func()) {
+				return testserver.NewDBForTest(t, testserver.ListenAddrHostOpt("0.0.0.0"))
+			},
+		},
 		{
 			name: "InsecureWithCustomizedMemSize",
 			instantiation: func(t *testing.T) (*sql.DB, func()) {